To study the effect of breakup coupling on fusion we have derived fusion cross sections in the framework of continuum discretised coupled channels (CDCC) method using the coupled channels code FRESCO for the systems 6,7Li+24Mg. The CDCC predicted fusion cross sections for the 7Li+24Mg system agree well with the experimental fusion data whereas for the 6Li+24Mg system the agreement is reasonable at below barrier energies. However, within the limits of the present work no definite conclusion could be obtained from the quality of agreement at above barrier energies for the 6Li+24Mg system.

Measurement of fusion cross sections for the Li-6,Li-7 + Mg-24 reactions by the characteristic gamma-ray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these gamma-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The relatively large difference between total cross sections and measured fusion cross sections at higher energies is consistent with the fact that other channels, in particular breakup, open up with an increase of bombarding energy. The breakup channel, however, appears not to have any influence on fusion cross sections. The critical angular momenta (l(cr)) deduced from the fusion cross sections are found to have an energy dependence similar to other Li-induced reactions.

The nucleus Tm-155 has been studied by a detailed in-beani gamma spectroscopy following the reaction Sm-144(N-14, 3n)Tm-155, at a beam energy, E-lab = 70 MeV, using a Compton suppressed gamma detector array. More than 25 new gamma transitions have been placed in the proposed scheme and the latter has been extended upto a spin-parity of (51/2(-)) at an excitation energy similar to 6 MeV. (C) 2007 Elsevier B.V. All rights reserved.

$^{30}\mathrm{P}$ has been studied by in-beam \ensuremath{\gamma}-spectroscopy following the fusion-evaporation reaction $^{16}\mathrm{O}$($^{16}\mathrm{O}$,$\mathit{pn}$) at ${E}_{\mathrm{lab}}=40$ MeV, using the Indian National Gamma (Clover) Array (INGA) up to moderate spins ($I=5$). Polarization measurements of seven gamma rays have been performed for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental data have been compared with the results from large basis cross-shell shell model calculations. The results for the negative parity states are especially important in this respect. Positive parity states indicate an onset of collectivity, whereas the negative parity states are members of \ensuremath{\nu}-\ensuremath{\pi} multiplets.

The high spin states of $^{143}\mathrm{Sm}$ have been studied by in-beam \ensuremath{\gamma}-spectroscopy following the reaction $^{130}\mathrm{Te}$($^{20}\mathrm{Ne}$,$7n$)$^{143}\mathrm{Sm}$ at ${E}_{\mathrm{lab}}=137$ MeV, using a Clover detector array. More than 50 new gamma transitions have been placed above the previously known ${J}^{\ensuremath{\pi}}=23/{2}^{\ensuremath{-}}$, 30 ms isomer at 2795 keV. The level scheme of $^{143}\mathrm{Sm}$ has been extended up to 12 MeV and spin-parity assignments have been made to most of the newly proposed level. Theoretical calculation with the relativistic mean field approach using blocked BCS method, has been performed. A sequence of levels connected by $M1$ transitions have been observed at an excitation energy \ensuremath{\sim}8.6 MeV. The sequence appears to be a magnetic rotational band from systematics.

Gamma ray spectra of two (p,γ) resonances have been utilised for the characterisation of the Clover detector at energies beyond 5MeV. Apart from the efficiency and the resolution of the detector, the shapes of the full energy peaks as well as the nature of the escape peaks which are also very crucial at higher energies have been analysed with special attention. Proper gain matching in software have checked deterioration in the energy resolution and distortion in the peak shape due to addback. The addback factors show sharp increasing trend even at energies around 11MeV.

Complete fusion excitation functions for B11,10+Tb159 have been measured at energies around the respective Coulomb barriers, and the existing complete fusion measurements for Li7+Tb159 have been extended to higher energies. The measurements show significant reduction of complete fusion cross sections at above-barrier energies for both the reactions, B10+Tb159 and Li7+Tb159, when compared to those for B11+Tb159. The comparison shows that the extent of suppression of complete fusion cross sections is correlated with the α-separation energies of the projectiles. Also, the two reactions, B10+Tb159 and Li7+Tb159 were found to produce incomplete fusion products at energies near the respective Coulomb barriers, with the α-particle emitting channel being the favoured incomplete fusion process in both the cases.

The high spin states of 35Cl have been studied by in-beam γ-spectroscopy following the fusion–evaporation reaction 12C(28Si,αp)35Cl at Elab=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd–fp shell gap seem to be essential for reliable reproduction of high spin states.

The lifetime of the 3163 keV, 7/2$^-$ isomeric state in $^{35}Cl$ that decays by a stretched M2 transition to the $3/2^+$ ground state, has been re-measured using the Doppler Shift Attenuation Method, by gating on the 1185 keV transition which directly feeds this state. This eliminates the uncertainties in the measurement arising from the direct feedings from the continuum. A mean life of 0.6$^{+0.5}_{-0.2}$ ps has been obtained from the present work. This is considerably smaller than the adopted value 45.3(6) ps. Implication of this major reduction in the lifetime has been pointed out.

The high spin level structure of Ag-104 has been extended to I-pi=20(+) and excitation energy of 7.159 MeV through the discrete line gamma-ray spectroscopy. The negative parity ground state band has been confirmed and extended to I-pi=18(-). Two new nonyrast dipole bands, one with positive and the other with negative parity, have been observed. The parities of the two bands have been established through polarization directional correlation measurement of the feed-out transitions from these bands. The level lifetimes have been measured in the ground state band and the positive parity dipole band. The measured total angular momenta and the B(M1) rates have been compared with the predictions of hybrid version of the tilted axis cranking. The B(M1) rates have also been compared with the values obtained from Donau's geometric formula. The tilted axis calculations give good overall agreement which suggests that all the three bands of Ag-104 exhibits magnetic rotation.

Measurement of fusion cross sections for the Li-7+O-16 reaction by the gamma-ray method has been done in the energy interval E-c.m.=12.5-23.6 MeV (where c.m. means center-of-mass). The gamma-ray data obtained at high bombarding energies are found to be in agreement with those obtained by the evaporation residue method. The present data, together with the previous gamma-ray data, show that there is no fusion suppression at energies below and near the Coulomb barrier.

The high spin states of Ag-103 have been populated through the Ge-76(Cl-35,alpha4ngamma)Ag-103 reaction using 132-MeV Cl-35 beam. The presence of a positive parity ground state band and two negative parity bands decaying predominantly by M1 transitions in Ag-103 has been confirmed. In addition, seven new crossover E2 transitions have been observed in the negative parity bands. The experimental B(M1)/B(E2) ratios are compared with the values obtained from the Donau geometric formula for the negative parity bands based on single particle configurations assigned from signature arguments. These ratios are also compared to those obtained from the hybrid version of tilted axis cranking. A systematic study of odd-Ag isotopes seems to indicate that the signature symmetry is retained in Ag-103 due to the shallow tilted minimum.

The Clover detectors in their addback mode are excellent tools for detecting high-energy gamma rays (⩾2MeV). The characteristics of these detectors, at energies above 2MeV, are usually determined from simulation data or from extrapolation of the empirical data. This is the first time that the characteristics of a Compton suppressed Clover germanium detector have been studied up to 5MeV using a radioactive 66Ga (T1/2=9.41h) source.

A critical analysis of the cross sections for the characteristic gamma rays of the residual nuclei following Li-6 +O-16 and Li-7+ O-16 reactions shows that if the breakup mechanism is supposed to be responsible for the limitation of fusion cross sections for these systems, then the large magnitude of the cross sections for the gamma rays cannot be accounted for.

Excited states of 68Ga have been investigated through the 55Mn(16O, 2pn) reaction at projectile energy 55 MeV. The level scheme has been extended up to 7.8 MeV. Altogether six new excited levels could be identified and twelve previously unobserved γ-transitions have been placed in the modified level scheme.

The cross sections for the characteristic γ-rays of the residual nuclei following 6Li+16O and 7Li+16O reactions have been measured at low energies with HPGe detectors. The fusion cross sections obtained from these γ-ray cross sections for both the systems are found to be in excellent agreement with the total reaction cross sections and this indicates that there is no inhibition of fusion cross sections for these systems at low energies, which is in contradiction to the results obtained from the measurement of evaporation residues and light particles. These cross sections also show good agreement with the IWBC (Incoming Wave Boundary Condition) model and the 1-D BPM (One-Dimensional Barrier Penetration Model) calculations. The critical angular momenta (lcr) dediced from the fusion cross sections are also found to have an energy dependence similar to other Li-induced reactions.

The high spin structure in the nucleus ${}^{62}\mathrm{Cu}$ has been studied using the reaction ${}^{50}\mathrm{Cr}{(}^{16}\mathrm{O},3pn)$ at a beam energy of 75 MeV. Most of the levels known from earlier experiments have been confirmed and the spin parity assignments of a few of them have been verified. A number of levels have been proposed extending the energy scheme up to about 7.6 MeV. A simple interacting boson-fermion-fermion model calculation has been performed to explain the observed energy spectrum.